Ok for some of you new people to this (like myself) i found another way to make npc's disappear after they are added to party.It was easier on my mind because i cant get switches to work the way i wantem to.
1.copy the map the npc is in
2.delete the npc in the copy
3.teleport in the same exact spot you talked to them
4.Change a few teleports (such as shops so the npc doesnt appear again)
5.Test and make sure u did it right lol :^^:
It works for me i use it most on indoor situations
Way too much work, if you don't know how switches work you are going to be in a lot of trouble. Take the time to look for a tut and learn or else you will have a very hard time trying to keep the players from going to the end of the game or places they shouldn't without following the proper course of the game.